U.S. patent application number 17/104660 was filed with the patent office on 2021-05-27 for active dampening gradient proportioning valve.
The applicant listed for this patent is Waters Technologies Corporation. Invention is credited to Sean Anderson, Timothy M. Raymond, Christopher Walden.
Application Number | 20210156829 17/104660 |
Document ID | / |
Family ID | 1000005289618 |
Filed Date | 2021-05-27 |
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United States Patent
Application |
20210156829 |
Kind Code |
A1 |
Raymond; Timothy M. ; et
al. |
May 27, 2021 |
ACTIVE DAMPENING GRADIENT PROPORTIONING VALVE
Abstract
Disclosed is a gradient proportioning valve for use in liquid
chromatography that includes a plurality of inlet ports configured
to receive a plurality of fluids, a manifold connected to each of
the plurality of inlet ports configured to mix the plurality of
fluids in a controlled manner to provide a fluid composition, the
manifold including a plurality of conduits internal to the
manifold, each of the plurality of conduits receiving fluid through
a respective one of the plurality of inlet ports, each of the
plurality of conduits operatively communicable to a respective
actuation mechanism configured to open and close each of the
plurality of conduits in a controlled manner, a common outlet port
configured to receive the fluid composition, and an active fluidic
dampening system configured to dampen unwanted fluidic pressure
pulses in the manifold. Liquid chromatography systems and methods
are further disclosed.
Inventors: |
Raymond; Timothy M.;
(Milford, MA) ; Walden; Christopher; (Milford,
MA) ; Anderson; Sean; (Dedham, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Waters Technologies Corporation |
Milford |
MA |
US |
|
|
Family ID: |
1000005289618 |
Appl. No.: |
17/104660 |
Filed: |
November 25, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62941236 |
Nov 27, 2019 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 30/34 20130101;
G01N 2030/347 20130101 |
International
Class: |
G01N 30/34 20060101
G01N030/34 |
Claims
1. A gradient proportioning valve for liquid chromatography
comprising: a plurality of inlet ports configured to receive a
plurality of fluids; a manifold connected to each of the plurality
of inlet ports configured to mix the plurality of fluids in a
controlled manner to provide a fluid composition, the manifold
including a plurality of conduits internal to the manifold, each of
the plurality of conduits receiving fluid through a respective one
of the plurality of inlet ports, each of the plurality of conduits
operatively communicable to a respective actuation mechanism
configured to open and close each of the plurality of conduits in a
controlled manner; a common outlet port configured to receive the
fluid composition; and an active fluidic dampening system
configured to dampen unwanted fluidic pressure pulses in the
manifold.
2. The gradient proportioning valve of claim 1, wherein the active
fluidic dampening system includes an active pulse dampening
actuator separate from the respective actuation mechanisms
configured to actively introduce additional pressure pulses into
the manifold to destructively interfere with the unwanted fluidic
pressure pulses in the manifold.
3. The gradient proportioning valve of claim 1, wherein the active
fluidic dampening system includes a control system configured to
alter the timing of opening and closing by the respective actuation
mechanisms to destructively interfere with the unwanted fluidic
pressure pulses in the manifold.
4. The gradient proportioning valve of claim 1, further comprising:
the plurality of the respective actuation mechanisms, wherein each
of the plurality of respective actuation mechanisms is a voice coil
actuator valve, and wherein the fluidic dampening system includes
the voice coil actuator valves.
5. The gradient proportioning valve of claim 2, wherein the active
pulse dampening actuator includes a control system built into the
valve for controlling the active pulse dampening actuator.
6. The gradient proportioning valve of claim 5, wherein the control
system is configured to operate with a feedback loop to ensure
proper dampening of the unwanted fluidic pressure pulses in the
manifold.
7. The gradient proportioning valve of claim 5, wherein the control
system includes a communication device configured for at least one
of sending and receiving control signals from a liquid
chromatography system.
8. The gradient proportioning valve of claim 7, wherein the
communication device is configured to receive an input signal in
response to an unwanted pressure response caused by one or more of
the actuation mechanisms.
9. The gradient proportioning valve of claim 2, wherein the active
pulse dampening actuator is located downstream from the respective
actuation mechanisms and upstream from the common outlet port.
10. The gradient proportioning valve of claim 3, wherein the
control system is a dithering control unit built into the
valve.
11. The gradient proportioning valve of claim 10, wherein the
dithering control unit includes a communication device configured
for at least one of sending and receiving control signals from a
liquid chromatography system.
12. The gradient proportioning valve of claim 10, wherein the
dithering control unit is configured to reduce quantization errors
by purposefully introducing consistent pressure noise.
13. A method of mixing fluid in liquid chromatography comprising:
providing a gradient proportioning valve; receiving a plurality of
fluids in a plurality of inlet ports of the gradient proportioning
valve; mixing the plurality of fluids in a controlled manner within
a manifold of the gradient proportioning valve to provide a fluid
composition, the manifold including a plurality of conduits;
opening and closing each of the plurality of conduits in a
controlled manner; outputting the fluid composition from a common
outlet port of the gradient proportioning valve; and dampening
unwanted fluidic pressure pulses in the manifold with an active
fluidic dampening system.
14. The method of claim 13, further comprising: actively
introducing additional pressure pulses into the manifold and
destructively interfering with unwanted fluidic pressure pulses in
the manifold with an active pulse dampening actuator.
15. The method of claim 13, further comprising: altering the timing
of the opening and closing by a control system; and destructively
interfering with the unwanted fluidic pressure pulses in the
manifold by the altering.
16. The method of claim 15, further comprising ensuring, by the
control system, proper dampening of the unwanted fluidic pressure
pulses in the manifold with a feedback loop.
17. The method of claim 15, further comprising receiving, by the
control system, an input signal in response to an unwanted pressure
response caused by one or more of the actuation mechanisms.
18. The method of claim 13, wherein the opening and closing each of
the plurality of conduits in a controlled manner is performed by a
respective solenoid valve, the method further comprising:
mitigating unwanted fluidic pressure pulses created by the opening
and closing of the solenoid valve with a ceramic sealing valve
piston.
19. The method of claim 13, wherein the opening and closing each of
the plurality of conduits in a controlled manner is performed by a
respective voice coil actuator valve, the method further
comprising: dampening the unwanted fluidic pressure pulses with the
respective voice coil actuator valves; and opening and closing each
of the plurality of conduits at variable speeds with the voice coil
actuator valves.
20. A liquid chromatography system comprising: the gradient
proportioning valve of claim 1; an injector; a separation column;
and a detector.
Description
RELATED APPLICATIONS
[0001] This application is a non-provisional patent application
claiming priority to U.S. Provisional Patent Application No.
62/941,236, filed Nov. 27, 2019, entitled "Gradient Proportioning
Valve," which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to gradient proportioning
valves. More particularly, the invention relates to a gradient
proportioning valve having active dampening features, and
associated systems and methods.
BACKGROUND
[0003] Gradient proportioning valves (GPVs) are known for use in
low pressure mixing liquid chromatography systems (i.e. quaternary
systems). U.S. Pat No. 5,862,832 describes an exemplary prior art
GPV. Specifically, the GPV is responsible in the systems for
setting the desired solvent composition. A typical GPV includes
multiple solenoid valves mounted on a common manifold that open and
close at precise times with respect to the system pump cycle. Upon
opening and closing of GPV solenoid valves, pressure pulses are
introduced to the system. Pressure pulses are also caused by the
start and end of the intake stroke during the pump cycle. Such
pressure pulses can cause undesirable oscillations in the
compositional error of chromatography systems. These oscillations
therefore diminish compositional accuracy and performance of a
liquid chromatography system.
SUMMARY
[0004] In one embodiment, a gradient proportioning valve for liquid
chromatography comprises: a plurality of inlet ports configured to
receive a plurality of fluids; a manifold connected to each of the
plurality of inlet ports configured to mix the plurality of fluids
in a controlled manner to provide a fluid composition, the manifold
including a plurality of conduits internal to the manifold, each of
the plurality of conduits receiving fluid through a respective one
of the plurality of inlet ports, each of the plurality of conduits
operatively communicable to a respective actuation mechanism
configured to open and close each of the plurality of conduits in a
controlled manner; a common outlet port configured to receive the
fluid composition; and an active fluidic dampening system
configured to dampen unwanted fluidic pressure pulses in the
manifold.
[0005] Additionally or alternatively, the active fluidic dampening
system includes an active pulse dampening actuator separate from
the respective actuation mechanisms configured to actively
introduce additional pressure pulses into the manifold to
destructively interfere with the unwanted fluidic pressure pulses
in the manifold.
[0006] Additionally or alternatively, the active fluidic dampening
system includes a control system configured to alter the timing of
opening and closing by the respective actuation mechanisms to
destructively interfere with the unwanted fluidic pressure pulses
in the manifold.
[0007] Additionally or alternatively, the gradient proportioning
valve further comprises the plurality of the respective actuation
mechanisms, where each of the plurality of respective actuation
mechanisms is a voice coil actuator valve, and where the fluidic
dampening system includes the voice coil actuator valves.
[0008] Additionally or alternatively, the active pulse dampening
actuator includes a control system built into the valve for
controlling the active pulse dampening actuator.
[0009] Additionally or alternatively, the control system is
configured to operate with a feedback loop to ensure proper
dampening of the unwanted fluidic pressure pulses in the
manifold.
[0010] Additionally or alternatively, the control system includes a
communication device configured for at least one of sending and
receiving control signals from a liquid chromatography system.
[0011] Additionally or alternatively, the communication device is
configured to receive an input signal in response to an unwanted
pressure response caused by one or more of the actuation
mechanisms.
[0012] Additionally or alternatively, the active pulse dampening
actuator is located downstream from the respective actuation
mechanisms and upstream from the common outlet port.
[0013] Additionally or alternatively, the control system is a
dithering control unit built into the valve.
[0014] Additionally or alternatively, the dithering control unit
includes a communication device configured for at least one of
sending and receiving control signals from a liquid chromatography
system.
[0015] Additionally or alternatively, the dithering control unit is
configured to reduce quantization errors by purposefully
introducing consistent pressure noise.
[0016] In another embodiment, a method of mixing fluid in liquid
chromatography comprises: providing a gradient proportioning valve;
receiving a plurality of fluids in a plurality of inlet ports of
the gradient proportioning valve; mixing the plurality of fluids in
a controlled manner within a manifold of the gradient proportioning
valve to provide a fluid composition, the manifold including a
plurality of conduits; opening and closing each of the plurality of
conduits in a controlled manner; outputting the fluid composition
from a common outlet port of the gradient proportioning valve; and
dampening unwanted fluidic pressure pulses in the manifold with an
active fluidic dampening system.
[0017] Additionally or alternatively, the method further includes
actively introducing additional pressure pulses into the manifold
and destructively interfering with unwanted fluidic pressure pulses
in the manifold with an active pulse dampening actuator.
[0018] Additionally or alternatively, the method further includes
altering the timing of the opening and closing by a control system;
and destructively interfering with the unwanted fluidic pressure
pulses in the manifold by the altering.
[0019] Additionally or alternatively, the method further includes
ensuring, by the control system, proper dampening of the unwanted
fluidic pressure pulses in the manifold with a feedback loop.
[0020] Additionally or alternatively, the method further includes
receiving, by the control system, an input signal in response to an
unwanted pressure response caused by one or more of the actuation
mechanisms.
[0021] Additionally or alternatively, the opening and closing each
of the plurality of conduits in a controlled manner is performed by
a respective solenoid valve, and the method further includes:
mitigating unwanted fluidic pressure pulses created by the opening
and closing of the solenoid valve with a ceramic sealing valve
piston.
[0022] Additionally or alternatively, the opening and closing each
of the plurality of conduits in a controlled manner is performed by
a respective voice coil actuator valve, and the method further
includes: dampening the unwanted fluidic pressure pulses with the
respective voice coil actuator valves; and opening and closing each
of the plurality of conduits at variable speeds with the voice coil
actuator valves.
[0023] In another embodiment, a liquid chromatography system
includes a gradient proportioning valve having a plurality of inlet
ports configured to receive a plurality of fluids, a manifold
connected to each of the plurality of inlet ports configured to mix
the plurality of fluids in a controlled manner to provide a fluid
composition, the manifold including a plurality of conduits
internal to the manifold, each of the plurality of conduits
receiving fluid through a respective one of the plurality of inlet
ports, each of the plurality of conduits operatively communicable
to a respective actuation mechanism configured to open and close
each of the plurality of conduits in a controlled manner, a common
outlet port configured to receive the fluid composition, and an
active fluidic dampening system configured to dampen unwanted
fluidic pressure pulses in the manifold. The liquid chromatography
system further includes an injector; a separation column; and a
detector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and further advantages of this invention may be
better understood by referring to the following description in
conjunction with the accompanying drawings, in which like reference
numerals indicate like elements and features in the various
figures. For clarity, not every element may be labeled in every
figure. The drawings are not necessarily to scale, emphasis instead
being placed upon illustrating the principles of the invention.
[0025] FIG. 1 depicts a block diagram of a liquid chromatography
apparatus, in accordance with one embodiment.
[0026] FIG. 2 depicts a perspective view of a gradient
proportioning valve, in accordance with one embodiment.
[0027] FIG. 3 depicts a side cross sectional view of the gradient
proportioning valve of FIG. 2, in accordance with one
embodiment.
[0028] FIG. 4 depicts a schematic view of another gradient
proportioning valve having an active pulse dampener, in accordance
with one embodiment.
[0029] FIG. 5 depicts a schematic view of another gradient
proportioning valve having a plurality of voice coil actuators, in
accordance with one embodiment.
[0030] FIG. 6 depicts a schematic view of another gradient
proportioning valve having a dithering control unit, in accordance
with one embodiment.
DETAILED DESCRIPTION
[0031] Reference in the specification to "one embodiment" or "an
embodiment" means that a particular, feature, structure or
characteristic described in connection with the embodiment is
included in at least one embodiment of the teaching. References to
a particular embodiment within the specification do not necessarily
all refer to the same embodiment.
[0032] A gradient proportioning valve accommodates the flow of
fluids from external reservoirs into the valve for mixing in
appropriate proportions to form a liquid composition. In an actual
embodiment, such a valve may include four inlet valves ported to a
common outlet, the embodiment shown hereinbelow in FIG. 2 shows two
inlet valves ported to a common outlet. In terms of functionality,
each inlet valve may be a normally closed, solenoid actuated
diaphragm valve that is switched in a controlled manner to provide
the appropriate amount of fluid required in mixing the liquid
composition. The function of the overall valve is to provide a
continuous stream of a compositionally accurate mixture of
components, such as solvents in a high pressure liquid
chromatography (HPLC) implementation. The mixture may be provided
from the common outlet under flowing conditions, while not
interfering with the flow rate of the fluid input system, and
without changing or otherwise affecting the quality/composition of
the fluids input for mixing.
[0033] Embodiments of the gradient proportioning valve described
herein may be configured to actively dampen or otherwise reduce
pressure pulses that occur due to the opening and closing of
channels in the fluidic systems of the valve, and in the valve
itself. Such pressure pulses have been found to cause large,
sinusoidal oscillations in compositional error. Active dampening
may include dampening these fluidic pressure pulses with an active,
powered, and/or controlled device. Thus, the gradient proportioning
valves described herein may be configured to provide improved
compositional accuracy across an entire solvent composition range.
This improved compositional accuracy may be particularly important
at higher flow rates.
[0034] FIG. 1 is a block diagram of an exemplary liquid
chromatography system 100, suitable for preparative- or
process-scale liquid chromatography, in accordance with one
embodiment of the invention. The system 100 is an exemplary system
within which gradient proportioning valves may be included
according to the embodiments described herein. The apparatus 100
includes four solvent reservoirs 1A, 1B, 1C, 1D, a gradient
proportioning valve 2, an inlet manifold valve 3, a pump 4, a
solvent mixer 5, an injector 8, a separation column 6, a detector
7, and a control unit 9. The gradient proportioning valve 2
represents a valve that includes one or more of the dampening
features described herein. Thus, the gradient proportioning valve 2
may be any of the gradient proportioning valves shown in FIGS. 2-6
and described herein below.
[0035] In operation, the gradient proportioning valve 2 and the
pump 4, in response to control of the control unit 9, select and
draw one or more solvents from the reservoirs 1A, 1B, 1C, 1D. The
gradient proportioning valve 2 may be operated, in response to
control of the control unit 9, to provide a selected solvent
composition, which is optionally varied in time, for example, to
implement gradient-mode chromatography. The solvent mixer 5 is any
suitable mixer, including known passive and active mixers. The
injector is any suitable injector 8, including known injectors, for
injecting a sample into the solvent flow. The injector 8 is
optionally disposed at alternative locations in the solvent flow
path, as will be understood by one having ordinary skill in the
liquid-chromatography arts. The inlet manifold valve 3 is connected
to an outlet tube from the gradient proportioning valve 2, and to
two inlet tubes connected to the pump 4, to supply solvent to the
two piston chambers. The inlet manifold valve 3 optionally includes
a sample injector, to inject samples into the solvent prior to its
entry into the pump 4. The control unit 9--including, for example,
a personal computer or workstation--receives data and/or provides
control signals via wired and/or wireless communications to, for
example, the gradient-proportioning valve 2, the pump inlet
manifold 3, the pump 4, and/or the detector 7. The control unit 9
supports, for example, automation of sample processing. Moreover,
the control unit 9 may be configured to control one or more of the
active fluidic dampening system(s) described herein, as described
herein below. The control unit 9, in various illustrative
embodiments, is implemented in software, firmware, and/or hardware
(e.g., as an application-specific integrated circuit). The control
unit 9 includes and/or is in communication with storage
component(s).
[0036] Suitable implantations of the control unit 9 include, for
example, one or more integrated circuits, such as microprocessors.
A single integrated circuit or microprocessor in some alternative
embodiments includes the control unit 9 and other electronic
portions of the apparatus 100. In some embodiments, one or more
microprocessors implement software that enables the functions of
the control unit 9. In some embodiments, the software is designed
to run on general-purpose equipment and/or specialized processors
dedicated to the functionality herein described.
[0037] In some implementations of the system 100, the control unit
9 includes a user interface to support interaction with the control
unit 9 and/or other portions of the system 100. For example, the
interface is configured to accept control information from a user
and to provide information to a user about the system 100. The user
interface is used, for example, to set system control parameters
and/or to provide diagnostic and troubleshooting information to the
user. In one embodiment, the user interface provides networked
communication between the system 100 and users located either local
to the operating environment or remote from the operating
environment. The user interface in some implementations is used to
modify and update software. In view of the description of
illustrative embodiments provided herein, it will be apparent to
one having ordinary skill in the separation arts that various other
configurations and implementations of control units can be utilized
in other embodiments of the invention to provide automated control
of process-scale and preparative-scale chromatography.
[0038] The pump 4 may be configured to provide solvent at pressures
of at least 500 psi, or 1,000 psi, or 5,000, psi 10,000 psi or
greater. The pump includes any suitable piston-based pump,
including known pumps, such as available from Waters Corporation,
Milford, Mass. The column 6 is any column suitable for
process-scale and preparative-scale chromatography. The column
contains, for example, any medium suitable for such a purpose,
including known media. The sorbent material is selected from any
suitable sorbent material, including known materials such as silica
or a mixture of silica and a copolymer such as an alkyl compound.
The solvents are any solvents suitable to a desired separation
process, including known solvents.
[0039] Again, the system 100 described above is meant to be an
exemplary liquid chromatography system in which various embodiments
of the gradient proportioning valves may be deployed. However, the
gradient proportioning valves described herein may be implemented
in any system in which gradient fluid mixing is performed. For
example, in a liquid chromatography quaternary system, after the
solvent reservoirs 1A, 1B, 1C, 1D, the next component the solvent
goes into may be a degasser chamber. From there, the solvent may
enter the gradient proportioning valve 2. After the gradient
proportioning valve 2, the solvent may then go through a check
valve to the pump (i.e. with no inlet manifold valve). Any liquid
chromatography system configurations which may deploy a gradient
proportioning valve are contemplated for incorporation of the
principles described herein.
[0040] Referring now to FIG. 2, a perspective view of a gradient
proportioning valve 2A is shown, in accordance with one embodiment.
The gradient proportioning valve 2A includes accumulators 19A, 19B
located directly adjacent to switching valves 17A, 17B, on the side
closest to the reservoirs 10A, 10B. It should be understood that
embodiments of the gradient proportioning valve 2A may include two
additional accumulators and switching valves (not shown) located on
the two open sides of the gradient proportioning valve 2A, thereby
connecting the gradient proportioning valve 2 to two additional
reservoirs, such as the reservoirs 1C, 1D shown in FIG. 1. Each of
the accumulators 19A, 19B may include a soft-walled flexible
plastic tube 50 of generally circular cross-section. As shown, the
accumulator tube 50 may be adapted at an end closest to the valve
inlet to snugly slide over a rigid plastic connector 52. A
connecting tube 54 may be implemented at the opposite end of the
accumulator tube to hold a relatively long length of flow tubing 56
that connects the valves with the reservoirs 1A, 1B. The end of the
accumulator tube adjacent to the connecting tube may be caused to
assume approximately the cross-section of a flattened ellipse 55
which may allow a significant internal volume change to occur in
the accumulator tube, with little change in pressure thereby
allowing the accumulator to overcome the effects of hydraulic
inertia.
[0041] FIG. 3 depicts a side cross sectional view of the gradient
proportioning valve 2A of FIG. 2, in accordance with one
embodiment. The gradient proportioning valve 2A includes a valve
manifold 10 that accommodates the flow of fluids from external
reservoirs (not shown). For the sake of clarity of the discussion
hereinafter, the illustrative valve described herein has the
capacity to mix only two input fluid streams. However, the features
described herein may be applied to valves mixing, for example, four
or more input fluid streams. The input fluid streams to be mixed
are received from the reservoirs and are introduced into the valve
at inlet ports 12. Fluids from the respective reservoirs, such as
solvents used in HPLC as known in the art, flow into respective
inlet ports 12 and thereafter flow through respective inlet
conduits 14 in the manifold 10 into respective accumulator volumes
or chambers 16.
[0042] The integral accumulator chambers 16, as well as the inlet
ports 12 and inlet conduits 14, are appropriately dimensioned as a
function of the flow rate of the valve application. The chamber 16
is frustum-shaped having a conical-base opposed to the inlet
conduit 14. The chamber is shaped to maximize the surface area of
the diaphragm (for compliance), and the inlet conduit 14 is
positioned to allow for the best swept volume geometry.
Accordingly, the chamber 16 also has a smooth transition from
larger to smaller cross-section. The placement of the chamber is
such that the fluidic resistance between a valve diaphragm 40
(discussed hereinafter) and the accumulator is minimized. Fluid
flowing through the conduit 14 flows perpendicular to the
conical-base, into the chamber 16 to confront the base or back of
the chamber 16.
[0043] An accumulator diaphragm 18 is positioned at the
conical-base or back of the chamber 16, opposite the inlet conduit
14. The diaphragm 18 in this illustrative embodiment, is a 0.002
inch thick film formed of Polytetrafluoroethylene (PTFE) laminated
on each side with Fluorinated Ethylene Propylene (FEP).
[0044] The diaphragm, as with all components in the fluid path of
the present illustrative embodiment, is formed of materials that
are functionally unaffected by a full range of organic solvents and
aqueous solutions of acids, bases, salts, surfactants, etc. and
other phase modifiers that may be used in any mode of liquid
chromatography. The diaphragm 18 effects a membrane or compliant
member at the back of the accumulator chamber 16 to allow internal
volume changes in the chamber to occur with little change in
pressure. Accordingly, as with the less advantageous accumulator
tubes of the prior art, the valve can overcome the effects of
hydraulic inertia. The compliance and damping of the diaphragm are
optimized for the applications flow characteristics, as will be
appreciated by those skilled in the art.
[0045] An oversized bore 20 behind the back of the conical-base or
back of the accumulator chamber 16 is configured to receive the
diaphragm 18 for clamping and sealing the diaphragm tightly
therein. A seating surface 22 interior to the bore 20 provides an
abutment against which the diaphragm seats. A sealing groove 24 is
disposed in the seating surface 22 and provides a portion of the
single seal effected in the implementation according to the
invention. A cylindrical sealing plug 26 formed of stainless steel,
includes a sealing ridge 28 that fits tightly into the sealing
groove 24 to seal the diaphragm in the bore 20 when the plug 26 is
engaged against the seating surface 22 with the diaphragm
sandwiched therebetween.
[0046] Preferably, the sealing plug 26 is dimensioned to fit
snugly, yet slidably within the bore 20. The plug 26 is held in
place by a clamping plate 30 which is mechanically attached to the
valve manifold such as by a screw 32. Additional mounting holes 33
are provided in the clamping plate 30 to facilitate the mechanical
fastening of the clamping plate to the valve manifold 10. In this
illustrative embodiment, resilient members such as belleville
springs 34 or washers are disposed between the sealing plug 26 and
the clamping plate 30, to provide some resiliency.
[0047] The diaphragm according to the invention overcomes hydraulic
inertia while minimizing the volume of fluid in the valve that is
exposed to potential air permeation, by limiting the surface area
of the diaphragm that is exposed to ambient air. In contrast to the
prior art wherein the entirety of the accumulator tubes were
exposed and the volumes of fluid therethrough subjected to ambient
air permeating the tubes, the diaphragm according to the present
invention is only exposed to ambient in a limited manner.
Atmospheric ports 36 are provided in the clamping plate 30 to
permit ambient air at the back of the diaphragm 18. While exposure
to ambient air is necessary for the diaphragm to perform its
intended function, the reduced surface area exposed within the
atmospheric ports significantly limits permeation of air through
the diaphragm.
[0048] As briefly described hereinbefore, input fluid streams to be
mixed are received from reservoirs and are introduced into the
valve manifold 10 at inlet ports 12. Fluids from the respective
reservoirs flow into respective inlet ports 12 and thereafter flow
through respective inlet conduits 14 in the manifold 10 into
respective accumulator volumes or chambers 16.
[0049] In the respective integral accumulator chambers 16 the
fluids to be mixed encounter the compliant diaphragm which allows
internal volume changes in the chambers to occur with little change
in pressure so that the valve can overcome the effects of hydraulic
inertia. The fluids to be mixed flow out of the chambers 16 through
chamber ports 38 whereupon the fluids are available at switched
valve diaphragms 40. The valve diaphragms are reciprocated by
switched valves as known in the art. The controlled switching of
the valve diaphragms determines the proportion of a respective
fluid that is received in a common port 42 within the valve
manifold 10. The respective fluids are mixed in their respective
proportions in the common port 42 and are available at an outlet
port 44 for downstream processing as known in the art.
[0050] Although only a two input valve is described in the
illustrative embodiment herein, it will be appreciated that the
concepts according to the invention could be implemented in a valve
having any number of inlet ports for mixing a liquid
composition.
[0051] While the diaphragm described herein is formed of
FEP-PTFE-FEP laminated, it will be appreciated that other materials
can be implemented to effect a diaphragm, such as thin stainless
steel, various composite materials, rubber or the like.
[0052] Although the sealing plug in the illustrative embodiment is
a cylindrical plug formed of stainless steel, it will be
appreciated that alternative sealing mechanisms can be implemented
while permitting ambient pressure at the back of the diaphragm,
such as spongy materials, cylindrically shaped composite material
or the like. Furthermore, while the sealing plug effects a tight
seal by having a sealing ridge that seats in a sealing groove in a
bore receiving the plug, it will be appreciated that the groove
could be in the plug and the ridge on a surface of the bore.
[0053] The embodiments of the gradient proportioning valve 2A
include an active fluidic dampening system including one or more
active dampening mechanisms, systems or methods, configured to
actively dampen unwanted fluidic pressure pulses in the manifold.
Thus, the gradient proportioning valve 2A may be configured to
actively dampen or otherwise reduce pressure pulses that occur due
to the opening and closing of channels in the fluidic systems
associated with the valve 2A, and within the valve 2A itself. This
active dampening may be configured to reduce pressure pulses that
occur due to, for example, the activation of the solenoid valves
17A, 17B. Using the below described active fluid dampening
system(s), improved compositional accuracy across an entire solvent
composition range may be provided.
[0054] FIG. 4 depicts a schematic view of another exemplary
gradient proportioning valve 2B having a fluidic dampening system
that includes an active pulse dampener 200, in accordance with one
embodiment. As shown, the gradient proportioning valve 2B includes
a manifold 210 having four inlet ports 212, each connected to a
respective solenoid valve 217 through respective inlet conduits
214. The solenoid valves 217 each include a port 242 that transfers
fluid to the active pulse dampener 200. The active pulse dampener
200 may be located prior to mixing fluid, after mixing, or during
mixing. The active pulse dampener 200 may be located downstream
from the solenoid valves 217 of the system. The active pulse
dampener 200 may be separate from the respective actuation
mechanisms (i.e. the solenoid valves 217) and may be configured to
actively introduce additional pressure pulses into the manifold 210
to destructively interfere with the unwanted fluidic pressure
pulses created by the solenoid valves 217 and/or the manifold.
Whatever the embodiment, the active pulse dampener 200 may be
located in the manifold 210 prior to the fluid being transported to
an outlet port 244.
[0055] The active pulse dampener 200 may further include a built in
microprocessor or control system configured to control the active
pulse dampener 200. Alternatively or additionally, the active pulse
dampener 200 may be in communication with the control unit 9 of the
liquid chromatography system 100. In this embodiment, the active
pulse dampener 200 may include a communication device for sending
and receiving control signals. In embodiments where the active
pulse dampener 200 operates in a self-contained manner,
communication with a system control unit, such as the control unit
9, may be unnecessary.
[0056] The active pulse dampener 200 may be housed in one singular
GPV housing. In other embodiments, the active pulse dampener 200
may be a component that is broken off from the primary GPV housing
into a standalone component. In either embodiment, the GPV may be a
solenoid valve, a different type of valve, or other mechanism, that
is configured to introduce an additional pressure signal which then
attenuates the overall pressure response. In some embodiments of
the active pulse dampener 200, one of the existing solenoid valves
on the GPV could be used to introduce the additional signal. In
other embodiments, one or more valves or some other mechanism may
be added to the GPV for the sole purpose of introducing the
additional signal. In whatever embodiment deployed, the active
pulse dampener 200 may be configured to actively attenuate the
pressure response.
[0057] The active pulse dampener 200 may be in communication with
the control unit 9 or include one or more additional or alternative
control systems. Contemplated implementations include obtaining, by
such a control system of the active pulse dampener 200, an input
signal in the form of an unwanted pressure response caused by
opening/closing the GPV and/or the pump intake. The control system
may then be configured to attenuate that signal and have the output
signal be a nice, flat, consistent pressure response. The active
pulse dampener 200 thereby is configured to act as the system
controller. The active pulse dampener 200 may be configured to take
the known input pressure response and actuate at such a time and in
such a manner that the output response is attenuated. A feedback
loop may be used by the control unit 9 or the one or more
additional or alternative control systems of the active pulse
dampener 200 to ensure that the response is attenuated in
accordance with predetermined or set expectations. The timing of
the active pulse dampener 200 may vary as the flow rate and solvent
composition changes (therefore changing the GPV actuation timing).
Such a feedback loop may help make sure the timing is sufficient
for the given flow rate, composition, and solvents being used.
[0058] FIG. 5 depicts a schematic view of another gradient
proportioning valve 2C having a plurality of voice coil actuators
717, in accordance with one embodiment. The gradient proportioning
valve 2C includes four inlet ports 712 connected to the voice coil
actuators 717 by respective inlet conduits 714. After the voice
coil actuator 717, common ports 742 connect the fluidic paths at a
mixing point. An outlet port 744 thereby transfers the mixed fluid
downstream. The voice coil actuator valves 717 may be included as
features of the fluidic dampening system of the gradient
proportioning valve 2C. The voice coil actuators 717 may be
configured to be opened and closed at variable speeds, which can be
used to reduce, dampen or eliminate the magnitude of pressure
pulses introduced to the system.
[0059] Referring to FIG. 6, a schematic view of another gradient
proportioning valve 2D is shown having a dithering control unit
800, in accordance with one embodiment. Similar to the embodiments
described above with the valves 2A-2C, the gradient proportioning
valve 2D includes four inlet ports 812. Each of the inlet ports 812
is connected to a respective fluid conduit 814 configured for
transporting fluid to a respective solenoid valve 817. The solenoid
valves 817 are configured to transport fluid to an outlet port 844
via respective fluid conduits 842 which converge into a single
stream or flow at or prior to the outlet port 844.
[0060] In one or more embodiments, the active fluidic dampening
system includes a control system embodied by the dithering control
unit 800 that is configured to alter the timing of opening and
closing by the respective actuation mechanisms, such as the
solenoid valves 817, to destructively interfere with the unwanted
fluidic pressure pulses in the manifold. The dithering control unit
800 may be a component of the gradient proportioning valve 2D or
may be a component of a greater liquid chromatography system, such
as the control unit 9, or may be a combination of both a control
unit contained within a gradient proportioning valve communicating
with a control unit of a greater liquid chromatography system. The
dithering control unit 800 may include a circuit board, chip or
other processing device for controlling the timing of the
respective solenoid valves 817, for example.
[0061] The dithering control unit 800 may be located in, for
example, the embodiment of the gradient proportioning valve 2A. In
such an embodiment, the solenoid valve 117A is located across from
the solenoid valve 117C on the outer body of the manifold 110,
while the solenoid valve 117B is located across from the solenoid
valve 117D on the outer body of the manifold 110. The control
system may be configured to open an opposing valve at a precise
time when a primary valve opening creates a primary pressure pulse.
The opening of an opposing valve to a primary valve opening may be
done in order to purposefully create an opposing pressure pulse
that destructively interferes with the primary pressure pulse. This
mitigation may occur prior to or at a mixing point. The opening of
the opposing valve may occur simultaneous to, or immediately
following, the primary opening of the first valve. In still other
embodiments, the control system may control a separate pulse
introducing valve structure that is separate from the various
solenoid valves (e.g. 117A, 117B, 117C, 117D) in the gradient
proportioning valve.
[0062] In still other embodiments, the active fluidic dampening
system and/or the dithering control system 800 may be configured to
purposefully introduce pressure noise into the system in order to
reduce quantization errors. This purposefully introduced noise may
be introduced through consistently opening and closing the solenoid
valves in a manner that creates a consistent noise that mitigates
pressure pulses. While the control system for altering the timing
of the opening and closing of respective actuation mechanisms
and/or purposefully introducing noise has been described with
reference to FIG. 6, such systems and methods may be utilized in
combination with any of the other gradient proportioning valve
embodiments described herein, or combinations thereof.
[0063] Embodiments of the invention further contemplate methods of
mixing fluid using the principles described herein above. Methods
of mixing fluid may first include providing a gradient
proportioning valve consistent with one or more of the principles
described herein and/or a liquid chromatography system having such
a gradient proportioning valve. Methods may include receiving a
plurality of fluids in a plurality of inlet ports of the gradient
proportioning valve and mixing the plurality of fluids in a
controlled manner within a manifold of the gradient proportioning
valve to provide a fluid composition, the manifold including a
plurality of conduits. Methods may include opening and closing each
of the plurality of conduits in a controlled manner and outputting
the fluid composition from a common outlet port of the gradient
proportioning valve.
[0064] Methods may further include dampening unwanted fluidic
pressure pulses in the manifold with an active fluidic dampening
system.
[0065] In some embodiments, the opening and closing each of the
plurality of conduits in a controlled manner is performed by a
respective solenoid valve, and the method further includes
absorbing unwanted fluidic pressure pulses created by the opening
and closing of the solenoid valve with an energy absorbing solenoid
armature stop located in at least one of the respective solenoid
valves.
[0066] In some embodiments, methods may include actively
introducing additional pressure pulses into the manifold and
destructively interfering with unwanted fluidic pressure pulses in
the manifold with an active pulse dampening actuator.
[0067] In some embodiments, methods may include altering the timing
of the opening and closing by a control system, and destructively
interfering with the unwanted fluidic pressure pulses in the
manifold by the altering.
[0068] In some embodiments, opening and closing each of the
plurality of conduits in a controlled manner is performed by a
respective solenoid valve, and the method further includes
mitigating unwanted fluidic pressure pulses created by the opening
and closing of the solenoid valve with a ceramic sealing valve
piston.
[0069] In some embodiments, the opening and closing each of the
plurality of conduits in a controlled manner is performed by a
respective voice coil actuator valve, and the method may include
dampening the unwanted fluidic pressure pulses with the respective
voice coil actuator valves, and opening and closing each of the
plurality of conduits at variable speeds with the voice coil
actuator valves.
[0070] While the invention has been shown and described with
reference to specific embodiments, it should be understood by those
skilled in the art that various changes in form and detail may be
made therein without departing from the spirit and scope of the
invention as recited in the accompanying claims. Further, while
various embodiments of active forms of fluidic dampening of
pressure pulses have been described in detail, these embodiments
may be employed in unison, or in combination with some or all of
the features described herein being incorporated into a single
gradient proportioning valve. Still further, the active forms of
fluidic dampening of pressure pulses can be supplemented in
combination with one or more passive forms that require no power
and/or control systems to function.
* * * * *